Production of allyl chloride



raoiopoa'iorg or a art. 002: 1

Walter Flemming and Gerhard Stein, Ludhaien-on-the-Rhinc, Germany,

assignora, by

mesne assients, to General Aniline & Corporation, New York, N. 3., acorporation of Delaware No Drag. Application .luly e, 193s, Serial No.

2ll7,'ii9. in Germany July 29, 193':

propylchlorlde alone or in admixture with each other or with propyleneat temperatures between about 500 and about 700 C., and causing thereaction to proceed with the aid of metallic contact catalysts which areindifferent to the action of hydrogen chloride.

Any propylchloride formed in addition to allyl chloride or remainingunchanged in the said process may subsequently be converted into allylchloride by the removal of hydrogen. This may be efiected'for example bysubjecting them again to the said treatment or splitting ofi hydrogentherefrom by treatment with agent binding hydrogen at high temperatures,whereby, contrary to expectation, the halogen remains in the molecule.

When the said reaction is carried out at comparatively low speeds offlow, it may happen that an undesirable reaction between the reactantstakes place in the gas mixture before the catalyst zone is reached; thereaction then takes place somewhat in the same way as a flame strikingback, strong formation of carbon black thus taking place. The speedof-fiow must therefore always be relatively high and, indeed, higherthan the speed of flame propagation. The reaction then takes place inthe desired manner only after reaching the front part of the catalystorin a relatively small zone situated on the catalyst or at its end.

As catalysts there are used metals or mixtures of metals or alloys whichundergo no reaction or no appreciable reaction with hydrogen chloride,

a claims" (cl. 260-654) tallic constituents. The catalysts arepreferably used in the form of netting, rolled-up netting. spirals,threads, granules, balls or cuttings. Shaped carrier material may alsobe provided with a coating of good thermal conductivity of metals ormetal alloys suitable as catalysts;

Their resistance to chemical attack may advantageously be increased by athin coating or graphitic carbon (lustrous black carb'on) which may beproduced on the surface of the catalyst for' example by burning inacoating of brown coal tar.

The mixing proportions of chlorine and the propane or propyl chlorideserving as initial material are preferably so chosen. that the chlorineis present in a smaller amount than corresponds to the theoreticalamount. For example it is advantageous to use a proportion of from about2 to 3 molecular proportions of propane to 1 molecular proportion ofchlorine or 3 molecular proportions of propyl chloride to'l molecularproportionof chlorine.

It is advantageous to introduce the chlorine and the propane or propylchloride to be reacted separatelyinto the reaction chamber and to mixthem a short distance in front of the catalyst. This may readily beeffected through suitable nozzles. The starting materials may separatelybe preheated before the reaction, or it may be suflicient to preheatpropane or propyl chloride alone and to then admix them with coldchlorine. The temperature should be sochosen that the mixture ispreheated to at least 150 C. Thepreheated mixture is now led with highspeed of flow into the reaction chamber, in which the metal catalyst issituated. The catalyst is heated, before starting the reaction to atleast 350 0., advantageously to reaction temperature between 500 andabout 700 C. The reaction commences after' a. short time and it remainslimited to a small zone of the catalyst which is continuously It isusual to work at normal pressure, but it is I possible to carry out thereaction at reduced orincreased pressure. Diluent inert gases, such asnitrogen may also be used. The reaction gases obtained are cooled afterleaving the reaction chamber, whereby a part of the allyl chlorideformed separates; the part which does not separate is separated from thehydrogen chloride formed, preferably with water in washing towers.

dried and separated by strong cooling or compression.

The following examples will further illustrate.

how our present invention may be carried out in practice but theinvention is not restricted .to.

these examples.

' Example 1 A rolled-together chromium-nickel wire netting is chargedinto the rear part of atube of V2A-steel (a corrosion-resistant steelcontaining from 15 to 20 per cent of chromium, from 5 to 9 per cent ofnickel and from 0.1 to 0.3 per cent-o! car-Mn). in e trout portion orthe tube. chlorice is led by means of a narrow tube provided with save aopenings. Over this chlorine inlet tube there fi propane in such anamount that a are is formed which contains proe' 4 and chlorine in themolccr proportion of 3:1.

The propane is preheated to 206 E. and the cat= alyst is at first heatedexternally to 400". C. n ion the mixture of propane and chlorine meetsthe catalyst, ignition takes place and there is formed in the front partof the catalyst a small glowing zone of from about i to 2 centimetersdepth which has a temperature of 600 C. By mainc circles? V worked upin'the r described above. The

Y condensate obtained contains 15 per cent of allyl chloride, 15 percent oi propyl chloride and per cent of higher chlotion products.

What we claim is:

1. The process of producing allyl chloride which comprises causing a useof one molec= The mixture leaving the reaction chamber is cooled.washed, driedand condensed. There is formed in a very good yield areaction product which contains 32 per cent of allyl chloride, 59

per cent of propyl chloride, 7.6 per cent of propylene chloride and 1.2per cent of higher chlorination products. Since the mixture leaving thereaction chamber, after removing the hydrogen chloride and addingfurther amounts 0! chlorine, is led over the same ,or a similar catalystunder about the said conditions, the fraction of allyl a chloride can bestill further considerably increased. r 4

Example 2 A mixture containing 35 per cent of propane and 65 per cent ofpropylene is substituted for the propane in the manner oi workingdescribed 1 in Example 1. /The catalyst in this case is first heatedonly to 350 C. Ignition immediately takes place at the catalyst andasmall glowing zone is formed within the catalyst which has atemperature oi about 600 C. By regulating the heat specially supplied,the temperature of the glowing zone is regulated to 630 C. The mixtureleaving the reaction chamber is cooled, washed, dried and condensed bystrong cooling to 20 below zero 0., the unchanged residual gas beingreturned in circulation. The condensate contains 58 per cent of allylchloride, 2'4 per cent of propyl chloride and about 18 per cent ofhigher chlorination products.

Example 3 oi propylene is heated to 250 0., and then led together with 1molecular proportion of chlorine through a tube as described in Example'1. The

catalyst was preheated to about 360 C. Ignition takes place at thecatalyst, and a small glowingaone is formed therewithin which has atemperature of about 610 C. The reaction gases are 7 about 700C. while Ie s ular proportion of chic to react in the gas phase with at least twomolecular proportions of a compound selected from the group co i -f s ofpropane and propyl chloride at a perature between about 500' about 200C'.,-while passingthe gas mixture through a reaction space allylchloride from the reaction gases formed.

2. The process of producing allyl chloride which comprises causing a,mixture of one molecular proportion of chlorine with at least twomolecular proportions of a compound selected from the class consistingof propane and propyl chloride, which mixture is preheated totemperatures above C. but below reaction temperature, to react at atemperature between about the gas mixture through a reaction spacecharged with a metal selected from the class consisting ofchromium-niclrel alloys and chromi-nickel-iron alloys which are table tothe action of hydrogen chloride, said metal being arranged within the Ireaction space so as to present a large surface area. to the gasmixture, and separating allyl chloride from therea'ction gases formed.

3. The process of producing allyl chloride which comprises causing onemolecular proportion of chlorine to react in the gas phase with at leasttwo molecular proportions oi propane at a temperature between about 500and about 700 C., while passing the gas mixture through a reaction spacecharged with a chromium-nickel alloy which is stable to the reaction ofhydrogen chloride and is arranged within the reaction space so as topresent a large surface area to the gas mixture, and separating allylchloridefrom the reaction gases formed. I

4. The process of producing allyl chlorid which comprises causing onemolecular proportion of chlorine to react in the gas phase with at leasttwo molecular proportions of propyl chloride at a, temperature betweenabout 500 and about 700 0., while passing the gas mixture through areaction space charged with a. chromium-nickel alloy which is stable tothe reaction of hydrogen chloride and is arranged within the reactionspace so as to present a large surface area to the gas mixture. andseparating'allyl chloride from

